英语周报20222.28答案

32.(12分,每空2分)(1)方法一:种植F1,并使F进行自交,将所结种子用稀碘液处理,观察颜色变化用稀碘液处理的种子,蓝黑色与红褐色的比例为3:1(或种植F1和糯性水稻进行测交,所结种∫用稀碘液处理,观察颜色变化用稀碘液处理的种子,蓝黑色与红褐色的比例为1:1)方法二:种植F1,取其花粉用稀碘液处理,(在显微镜下)观察颜色变化蓝黑色与红褐色的比例为1:12)将绿叶甘监与F紫叶什监杂交,观察子代屮甘蓝的叶色杂交子代中紫叶:绿叶=3:1【解析】(1)题干屮有四个信息:①非性和槠性由一对等位基因控制;②橫性米粒和花粉粒過稀碘液呈红褐色,非糯性的米粒和花粉粒迥稀碘液呈蓝黑色;③F:的水稻全为非糯性(显性);④分别以种子和花粉与经稀碘液处理后的颜色变化为观察指标通常情况下,验证基因分离定律可用自交和测交的方法,结合题中显色的特点,再结合题中对两种方法提出的要求,可以解答(2)紫叶与绿叶的分离比为15:1,是9:3:3:1的变式,即只有双隐性个体表现为绿叶,其他均为紫叶。题中已给自交结果,要验证这两对基因在传递时符合自由组合定律,应设计测交实验,涉及的两对基因分别用A/a、B/b表示,子代有四种基因型,AaBb、Aabb、aBb、aabb,比例为1:1:1:1,按上述自交子代表现型及比例推理,测交子代紫叶:绿叶=3:1。

第四部分写作第一节Dear Jack,Welcome to our school to study as an exchange studentAs for how to borrow books from the school libraryyou need to have your student ID card and present it to thelibrarian, who can register for you. Then you can go to thebookshelves to look for what you need. You can borrow 2books once and keep them for a week in order that you canhave enough time to finish reading them. If you haventread the book through, you can renew it. You' ll have topay for it if you get the book damaged or lost.hope all this can be of help to you. For morenformation, don,t hesitate to ask meLi Hua

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